Posts Tagged ‘methacholine

The relationship between M W/FEVj and reactivity of asthmatic airways may account for the presence of abnormal MW/FEVj ratios in some but not all asthmatic subjects; in this study, MW/FEVj ratios were clearly lower and SGawDI/SGawMW^ ratios were clearly higher in those asthmatic subjects with greater methacholine responsiveness. Worsening pulmonary function has also been associated […]

If so, repetitive mechanical stimulation of airways irritant receptors may have led to vagally mediated reflex bronchoconstriction. Alternatively, there is experimental evidence that a quick stretch will increase tension in isolated sensitized airways smooth muscle. If this is true in vivo, repetitive stretching of airway smooth muscle may have contributed to post-M W reductions in SGaw in […]

In our study, there were also significant correlations between MW/FEV! and the effects of lung volume history as well as between MW/FEVi and response to methacholine. Previous studies have shown that MW/FEV! values are often reduced in subjects with poor muscle strength or endurance, extrathoracic upper airway obstruction, and/or in the presence of suboptimal effort […]

Although Vtg values were significantly higher in the asthmatic subjects, Vtg clearly did not vary with volume history in either group. Accordingly, changes in SGaw with different volume histories reflected changes in airway resistance (and presumably, therefore, bronchomotor tone). In the stable asthmatic subjects (but not the normal individuals), a significant negative correlation was found […]

Results Spirometric Tests Compared with results in the asthmatic subjects, FEVi, FEV/FVC and MW were higher in the normal subjects (Table 1). The M W/FE V! ratio was also higher in the normal subjects. Using one-tailed and two-tailed analyses, the lower 95 percent confidence limits for a normal MW/FEVi were 34.8 and 33.0, respectively; 13/40 […]

Methacholine Bronchoprovocation Tests Twelve individuals from the stable asthmatic group participated in this phase of the study; six individuals had low MW/FEV, ratios, whereas the other six had normal MW/FEV, ratios. Methacholine was inhaled from a Wright nebulizer during two-min periods of tidal ventilation. Subjects wore a nose clip. Each period of tidal breathing of […]

Subjects Twenty nonsmoking normal subjects (ten men, ten women; mean age±SD = 37± 15 years) without history of allergic rhinitis, cardiopulmonary or systemic disease were studied. Forty stable asthmatic subjects (20 men, 20 women; age = 37 ± 13 years) also were studied. Criteria for the diagnosis of asthma were those established by the Committee […]